Electrical musical instrument



Jan. 3, 1939. v c. E. WILLIAMS 2,142,580

ELECTRICAL MUSGAL INSTRUMENT Filed March 6, 1933 4 Sheets-Sheet lgmc/1MM CHARLES E WlLLmms C. E. WILLIAMS ELECTRICAL MUSICAL INSTRUMENTFiled March 6, 1933 4 Shets-Sheet 2 CHARLES EWILLIAMS Jan. 3, 1939. C EwlLLlAMS 2,142,580

ELECTRICAL MUS IGAL INSTRUMENT FIG. 3

Jan. 3, 1939. c. E. WILLIAMS LECTRICAL MUSICAL INSTRUMENT Filed March 6,.1933 4 Sheets-Sheet 4 FIG FIC5-4- Firm FIGLS Bumm/vtm CH'ArzL'ESEWILLIAMS Y Mtv/MAL;

Patented Jan. 3, 1939 UNITED STATES ELECTRICAL PATENT OFFICE MUSICALINSTRUMENT of Delaware :Application March 6, 1933, Serial No. 659,667

comms.

kThis invention in general relates to electrical musical instruments andin particular to means for incepting, generating,l controlling,modulating,

selecting, combining and coupling alternating electrical currents forthe production of musical sounds when used with a suitable outputsystem, the Alatter ordinarily including amplifying and loud speakingsystems. An instrument con-A structed in accordance with thisspeciilcation may be'used in place of a pipe organ or as an orchestralinstrument or it may be used for accompanying and solo purposes. Y

Incorporated in this instrument are meansv for regulating the number andamplitude of harmonies inthe musical tones.

`Another object is to provide for the operation of the instrument whendesired, by more than one player.; at the same time by the use of aplurality of keyboards. These keyboards may be reproduced in whole or inpart to suit the frequency range required for'the individual player.

Another object is to provide means for producing avibrato.

Another object is to provide means for-monitoring and remote control ofvarious qualities in the music Vwhen produced in a concert hall withadditional features such as indicators to show the re1- ativeamplitudesof Asound Waves as received at a particular point in theconcert hall as well as the settings and adjustments of the remotecontrol devices.

In this invention alternating currents of audible frequency are producedby suitable generators and associated circuits. One generator isprovided for each frequency desired and all are operated continuouslyand connected to an amplifying and output control system or systems bymeans of one or a plurality of keying systems. Musical sounds areproduced in the speaker systems only when the keying systems areoperated.

By operating the generators Vcontinuously better frequency regulationand stabilization can be obtained than can behad with generators whichare keyed to produce intermittent operation.- Another advantage that canonlyv be' had with continuously operated generators is the availabilityof thev generated frequencies for use in combining with otherharmonically related frequencies to produce various wave forms withresultant tonal effects. This results in a reduction in the number oftone generators required and. permits of a simplified arrangement.

This instrument is provided withv means whereby one or more players mayplay it simultaneously using the entire frequency range. of theinstrument in whole or in part. For example, identical keyboards may beelectrically connected to the Igenerating system and to the outputamplifying system for operation by the different players, or, onekeyboard group may be of a type similar to 5 the present day pipe organmanual while other groups may be of a type shown in theaccompanying'illustrations and described in the following text.

This combination and arrangement permits of l a more simplifiedarrangement than has heretofore been obtainable by the use of individualgenerators for each tone vfrequency with associated generator groups toprovide harmonic frequencies for combination with the fundamental. In myl arrangement the harmonic components desired for any given tonefrequency are obtained by vintroducing the desired amount of harmonicenergy into the keying and amplifying system, said harmonic energy beingderived from other fundamental tone generators of the system.

Another advantage voi this system is that in the case where a pluralityof keyboards are operated in connection with the master generator systemthe" pitch of the musical tones regardless of which keyboard or playeris controlling the keying. In systems previously developed wherein acomplete system of generators is provided for each keyboard or playerdifficulty` is frequently experienced vin synchronizing frequencies. 1

In systems employed in similar musical instruments up to the presenttime wherein a multiplicity of generators are connected to the output oramplifying devices difficulty is experienced in maintaining consistentvolume or amplitude levels due to the fact that the output or loadimpedance varies with the number of units in parallel. In my arrangementthis is overcome to such a degree that it cannot be detected by the ear,by means of combining high impedance generator output circuits to workinto a succeeding shunt circuit of relatively low impedance.

Vibrato effects, better defined as frequency modulation, frequency andamplitude modulation in combination, or phase modulation, are at timesdesirable and necessary in the rendition of most compositions. Previousattempts to obtain this effect in electrical instruments of thisgeneraltype have resulted'in the production of a tremolo or 50 amplitudemodulation only. The latter, used extensively in pipe organs, is rnot asdesirable to those skilled or trained in the art of music as is avibrato eect.

Figure l is a schematic diagram of a typical will be identical 25circuit arrangement with continuously operated tone frequency generatorsharmonically related frequencies with switching and keying devices forconnecting the output to an amplifying and loud speaker system. Embodledin this arrangement are controls for both foot and hand adjustment ofvolume. i

Figure 2 shows an arrangement wherein tone frequencies are generated bymeans of electronic tube oscillators. 'I'his arrangement includes asystem of output coupling and control devices, a harmonic intercouplingsystem and multiple keying connections.

Figure 3 shows in addition to the devices of Figures 1 and 2 a method ofproducing a vibrato effect, means for tuning and a system of remotemonitoring controls for regulating output volume and tonal qualitieswith telltale indicating devices located in the vicinity of the playersor conductor.

Figures l to 9 inclusive show alternative arrangements of contacts topermit keying of the instrument by contacting with the hands.

The nature and scope of this invention can best be understood byreference to the drawings. In Figure 1 are shown tone frequencygenerators, indicated by IU, fZIl, JS and i600 which generatealternatingcurrents having frequencies of 100, 200, 300 and 400 respectively. Eachof these is connected to an output coupling device consisting ofvariable impedances 8a, Bb andc. This particular coupling system is usedin a manner-similar to that employed extensively in telephone andcarrier frequency systems. The impedances may be adjusted to regulatethe amplitude of the currents in either or both of the coupled circuitsor the degree of coupling desired. This is of particular value in thatlarge changes in output circuit impedance result in negligible effectsin the generator circuit. Similar generators which are necessary inconnection with the generators and system `shown are omitted from thedrawings, for sake of simplicity, but connections thereto are indicatedby f, fllt, JS, H200 and fito. ISa, Ib, IIc and ltd are contact devicescomplemental to the respective contact devices fI, f2, f3 and fli, whichin this arrangement illustrated bear the relation of fundamental andsecond, third and fourth harmonics. The gaps between contacts I6a, Ib,Ic and Id and the respective contact devices of fl, f2, f3 and ffl arearranged and connected in such a manner as to permit electricalconnection to be made with the hand or body, 1

or in any convenient manner, to complete the circuit across such gaps toterminal Il, allowing current to ow to the terminals of variableimpedance IB. The player may or may not be in contact at all times withthe conductor connecting to Il. The contact devices I6a, I6b, 16e and Idare shown in detail in various forms in Figures 4 to 8 inclusive. II isa variable impedance coupling device for regulating the degree ofintercoupling of a harmonic frequency to the fundamental tone frequency.Said harmonic component is obtained by connection to another tonegenerator whose frequency is such as to bear the required harmonicrelation to the fundamental. 1n all cases Where reference is made toharmonic frequencies it is the intention to consider as harmonicfrequencies all notes of the tempered musical scale that correspond tothe true note but which are modied or detuned a slight amount to permitthe use of ther instrument in various musical keys. It is the intentionthat either the true harmonic frequency or the corresponding temperedfrequency be considered herein as harmonic frequency. I0f2, IIJf3 andIllf are switches for the selection of second, third and fourthharmonics respectively; all switches bearing the same designation areoperated simultaneously by means of contact keys or magnets similar tostop switching arrangements used in pipe organs. In actual operation, ifthe required tonal quality necessitates fundamental and harmonicamplitude relations, such as fundamental IIIIJ, second harmonic 25 andfourth harmonic Il); switches I0f2 and lfli are closed, impedances IIwill be adjusted to limit the associated harmonics to the proper value,thereby obtaining the desired tone color. Keying of the fundamental plusthe second and fourth harmonics will beaccomplished by completing thecircuit through the associated keying contact devices Ia or Ib, etc.,means to that end being shown in Figures 4 to 9 inclusive. Inthe eventonly the fundamental tones are to be played all of the harmonic selectorswitches will remain open. The variable impedance I8, known herein asshunt load impedance, should be of value relatively low compared to thatof the generator output coupling device. This will permit of the outputcircuits of a plurality of generators being connected in parallel, withthe result that the volume of a given tone frequency will remain audiblythe same regardless of the number of tones being played simultaneously.This variable impedance I8, also serves as a maximum volume limiter. Itmay be adjusted prior to a performance to limit the volume from thespeaker system to that which will not overload the amplifying or speakersystem attached thereto and which is consistent with the music to beplayed. Such adjustment should be made with all other volume controlsset in a maximum position. A hand operated volume control locatedpreferably near or upon the instrument keyboard is indicated by variableimpedance I9 while 2D is a variable impedance for volume control withpedal or lever operating mechanism arranged by means of springs o rother similar devices to return to an off position when pressure isremoved. By means of these devices the volume can be controlled withinthe limits imposed by the variable impedance I8. Any suitable outputsystem may be employed, and in the drawings the same includes the audiofrequency amplifier, 2|, and the band pass or suppression filter 22,while 23 is a speaker selector system, and ZII and 25 represent loudspeakers. These devices are in themselves common in the electrical artand need no further description. Switch 3&1. and variable impedances 35aand 3th constitute a quick acting damper circuit connected in shunt withthe output system for the purpose of cutting the volume off or on, to a,denitepredetermined value or to zero value and at a rate determined bythe adjustment of the impedance elements. It is intended that it beattached to a pedal operated mechanismand operated by the player.

In Figure 2 a more detailed circuit arrangement may be found wherein aform of generator comprising an electronic tube I, inductances 2 and 3,condensers 4 and 'I are indicated. Inductance 3 and condenser Ilcomprise an oscillatory circuit. This oscillatory circuit in conjunctionwith the electronic tube and associated power source constitutes a meansfor incepting tonefrequency currents. Thisvgenerator is coupled to theoutput keying system by means-of coupling impedances la, 8b and 8c.These impedances are v arranged in such a manner that the magnitude oi'impedance included in the input circuit (side presented to thegenerator) Is low relative to the magnitude of impedance in the outputcircuit and are arranged to provide high attenuation between the inputand output, thereby providing a substantially constant load on thegenerator and thereby preventing undesirable` transients from beingproduced and combined with the tonefrequency currents as a result ofkeying. These transient currents would otherwise produce the effectknown as key thumps. 5 and 6 represent respectively plate and gridpotential sources as used in common practice with similar vacuum tubecircuits. Switches are operated by the player to produce frequency M00in the speaker system, switches 9a are operated to produce i200 whileswitches 9b when operated produce frequency f300. All switches bearingthesame designation are operated simultaneously either by means of onekey or by a relay operated by a key. Harmonic coupling devices IIregulate the tone color or timber by regulating the amplitude of theharmonic components. Switches IN2 are operated simultaneously by meansof contact keys or magnets similar to stops on the present day pipeorgan. With these switches closed the second harmonic of the associatedfrequency will be present when keying switches are closed. Similarlywhen the third harmonic is desired switches I0f3 are closed and couplingto the desired generator is regulated by associated coupling device II.Provision is made for varying the degree of harmonic coupling bycontrolling the flux density in the magnetic material within the fieldof impedances IIa.- This is accomplished by controlling the currentwhich energizes windings IIb; in case of the units for coupling ofsecond harmonics the switch I2 and variable'resistance I3 is used, whileswitch I4 and variable resistance I5 are used similarly for the thirdharmonic control circuit. Contact devices I6a, IIb and I6c previouslyreferred to are connected in parallel with switches 9, 9a and 9b in sucha manner that the circuits are completed to the terminal I'I by eitherthe switches or the keying contact devices.

Figures 4 to 9 inclusive show in detail some of the ways in which thekeying contacts may be arranged. In Figure 4 the keys shown are similarin arrangement to that of the standard piano or organ keyboard. The keyshowever may be either fixed or movable, preferably they are of aconducting material so that by contacting with the hand the circuit willbe completed to the contact rail to which is attached the other side ofthe circuit I'I. This rail or strip should also be of conductingmaterial. By contacting it with the thumb and varying the pressure orarea of contact the volume may be readily controlled as desired by theplayer. The form in which this principle may be applied may assumevarious designs for example that as shown in Figure 5 where the size andarrangement of keying contacts are different from that shown in Figure4, the principle of operation remains the same. Figure 6 shows a furthermodification wherein both sides of the circuit are terminated on eachkey in alternate order but spaced forinsulating purposes. By makingcontact on any two or more strips the circuit is completed. All shadedareas are connected to the common point Il while all other areasdesignated by the same identification number are interconnectedelectrically to the other side of the circuit. Figure 'I shows anotherform in which these contact areas may be arranged. In Figure 8 the twosides of the circuit are terminated in small areas insulated from eachother. All shaded portions are connected in common to the same side ofthe circuit, designated as Il. By placing the finger on the portionnearest the bottom of the illustration a lower contact resistance willresult as the area of contact is greater than when the finger is placedat the upper part of the key where the contact area is much less. Bytouching the key at the proper place the desired volume will result.Figure 9 shows an arrangement where multiple contacts are arranged sothat contact may be made to harmonic circuits as well as to thefundamental frequency. As in the previous illustrations the shadedportions are connected to the side of the circuit represented by I1. Thesmall insulated circular areas are differently marked to indicate towhich tone frequency they are electrically connected. Those marked inthe same manner as the areas desigmated fl are common to thefundamental, while f2, f3 and fl indicate the order of harmonicfrequency to which such areas are connected, respectively. The contactsare electrically connected to harmonically related sources in the samemanner as are the various contacts shown in keying devices I6a, IBb,etc., in Figures 2 and 3. By placing the finger on that portion at thebottom of the illustration where only contact with ,fI and Il ispossible the resultant tone will contain only the fundamental frequencywhereas contacting the upper portion of the key will complete theconnection to various harmonic frequencies as well as to thefundamental. The amplitude and number of harmonics will be relative tothe area exposed to the touch. This will permit a variation in tonalquality or color by the addition or elimination of harmonic content bymoving the finger over the key.

Figure 3 shows in a more simplified form all of the features previouslydescribed and in addition a means for obtaining tone-color by frequencymodulation of the generated frequencies to accomplish a vibrato effect.This may be accomplished by including in the oscillatory circuits ofeach generator a device well known to those versed in the art as amagnetic modulator. This device 32 consists essentially of a threebranch core 32a, upon the center branch of which is a controllingcircuit winding 32h supplied with modulated direct current from source 5and variable low frequency generator 30 as indicated or merely by thelatter source. The frequency of pulsating or alternating currentsupplied by 30 will correspond to the frequency of the vibrato and willbe for ordinary effects between two and ten cycles per second. By meansof frequency control 46 located conveniently to the player the vibratofrequency may be readily varied. The magnetic polarities of controlledcircuit windings 32o and 32d are such that none of the flux produced bythe tone frequency currents in these windings will flow through thecenter branch upon which is 4winding 32h, thereby impressing one currenton the other and, yet, obtaining zero magnetic coupling between thecontrolling and controlled circuits; thus, preventing intercoupling, orreaction, between tone frequency generators of the system. 326 is avariable impedance shunted across winding 32h to permit variation of thevoltage across this winding. In the event a pulsating or modulateddirect current is used in this circuit impedance 32h may also be used`for mak-lng slight adjustments in the frequency generated by the tonegenerator or oscillator I. This is accomplished by regulation of the uxdensity in core 32a which is one of the factors determining thefrequency of oscillations generated by I. I do not wish to be restrictedto the exact arrangement shown in this illustration. The vibratomodulating circuit may be coupled in a similar manner to any portion ofthe oscillatory circuit and have ultimately th same desired effect.Likewise the means for tone frequency adjustment will be effective ineither of these schemes.

I do not wish to be restricted to the exact means and circuitarrangement shown on the drawings. Identical results may be similarlyproduced by variations in capacity or by variations in inductance andcapacity in combination, said variations occurring at a ratecorresponding to the vibrato frequency. Also, there may be includedadditional means for combining with the above described frequencymodulation system, means for producing a variation in amplitude with'constant or variable phase relation with respect to the frequencymodulation. The amplitude modulation component may be produced by theuse of circuits and devices well known to those versed in theradio-electrical art.

An arrangement of controls 26, 21 and 28 is shown connectingrespectively to amplifier 2i, v-band lters 22 and speaker selector 23,said controls to be located at some point in a concert hall Where therendition of the music may be best judged or analyzed for the purpose ofeecting changes in relative volumes of the various tone frequenciesproduced by this and like instruments. Provision is also made fortelltale indicators at the conductors stand or withinthe vision of theplayers, to indicate the relative volumes -and the corrections as'applied from the monitoring and listening station. These controls andindicators may be of a type well known to those familiar with theelectrical art. Impedance device 33 may be inserted in some portion ofthe keying circuit where intermittent currents occur to reduce theundesirable eiects known as keying transients or key thurnps. In thisinvention wherein tone frequency generators or electronic tubeoscillators are used as prime sources of alternating current and thekeying is accomplished in the coupled output circuits there is a muchgreater freedom from keying transients than will be found in instrumentswherein keying is done by interruption of the oscillatory circuits or inthe power supply connections. In my keying arrangement the current andvoltage amplitudes at the points of interruption are relatively smallAcompared to those found in previous systems.

I claim:

1. In an electrical musical instrument for incepting and modulatingtone-frequency currents: a plurality of sources of tone-frequencycurrents; a source of vibrato-frequency current; and means forimpressing said vibrator-frequency current on said sources oftone-frequency current so as to produce vibrato eiects therein and for'preventing reaction of said tone-frequency current upon said source ofvibrato-frequency current, said means comprising a magnetic modulator.

2. In an electrical musical instrument for incepting and modulatingtone-frequency current: a plurality of sources of tone-frequencycurrent; a source of vibrato-frequency current; and means comprising amagnetic modulator and variable impedance associated with said modu- Vlator for impressing said vibrato-frequency curcepting and modulatingtone-frequency currents: a plurality of sources of tone-frequencycurrents;

a source of vibrato-frequency current; and means for impressing saidvibrato-frequency current on said plurality of sources of tone-frequencycurrents so as to produce vibrato effects in said tone-frequencycurrents and' for preventing reaction of any of said tone-frequencycurrents upon any of said sources, said means comprising a magneticmodulator.L

4. In an electrical musical instrument for incepting and modulatingtone-frequency currents: a plurality of sources of tone-frequencycurrents; a source of vibrato-frequency current; and means comprisingmagnetic modulators and variable impedances associated with saidmodulators fo'r impressing said vibrato-frequency current on saidplurality of sources of tone-frequency currents so as to produce vibratoeffects in said tone-frequency currents, for preventing reaction of anyof said tone-frequency currents upon any of said sources, and forregulating the frequencies of said tone-frequency currents.

5. In an electrical musical instrument, the combination of anoscillating vacuum tube circuit having capacitative and inductivereactances, the values of which control the frequency of oscillation ofsaid circuit, and vibrato frequency generating means coupled to one ofsaid reactances and operable periodically to vary' the effective valuethereof, thereby periodically to vary the frequency of the currentgenerated in said oscillating circuit to produce a vibrato eff ect.

6. In an electrical musical instrument, the combination of a pluralityof oscillating vacuum tube circuits each having capacitative andinductive reactances determining their respective frequencies ofoscillation, and vibrato frequency generating means coupled to one ofthe reactances of each of said circuits and operable periodically tovary the eective value thereof, thereby periodically to vary thefrequencies of the currents generated in said oscillating circuits toproduce a vibrato effect.

7. In an electrical musical instrument in which electrical generators ofthe frequencies of the musical scale are utilized to supply energy to anoutput circuit having means to translate electrical oscillationsintosound; a keyboard comprising an insulating member, and a pluralityof electrical contacts mounted on said insulating member and arranged tocontrol the transmission to the output circuit current from generatorsof substantially harmonically related frequencies, said contacts beingspaced suiiiciently close together that a plurality of them may besimultaneously contacted by a linger of the player and therebyselectively determine the tone quality of the note which is sounded.

8. In an electrical musical instrument for incepting and modulatingtone-frequency currents, a plurality of sources of tone-frequencycurrent, each of said sources comprising a vacuum tube oscillator havinga frequency controlling impedance, a source oi' vibrato-frequencycurrent, and means for impressing said vibrato-frequency current on saidimpedances of said sources oi! tone frequency current so as to vary thevalues of said impedances and thereby to produce vibrato eiects in thecurrent generated by said sources.

9. In an electrical musical instrument for incepting and modulatingtone-frequency current, a vacuum tube oscillator having an impedance thevalue of which is a factor in determining the frequency ct oscillationof the oscillator. said oscillator forming a source of tone-frequencycurrent, a source of vibrato-irequency current, and means for impressingsaid vibrato-frequency current on said impedance o! said source of tone-Irequency current so as to produce vibrato etects therein and forpreventing reaction oi said tonefrequency currents upon said source ofvibratofrequency current, said means comprising an element whichperiodically varies the eilfectiveness of said impedance.

CHARLES E. WILLIAMS.

